The trials of breast cancer have passed, the reconstruction was a success, the free flap reconstruction looks natural and is settling well and maybe even the nipple reconstruction is done. But what about the DIEP flap donor site issues that can crop up?
There is no denying that abdominal bulges and hernias are possible risks after the harvest of either TRAM or DIEP flaps for breast reconstruction. But why can it happen, how can it be avoided, and is the DIEP flap really that much better than a TRAM flap when it comes to preventing bulges and hernias?
Well, lets start at the top of that little list and work our way down.
1. WHY CAN BULGES AND HERNIAS DEVELOP AT THE DIEP FLAP DONOR SITE?
Well, this is pretty simple. The abdominal wall protects and supports the organs in the abdomen. Without the abdominal wall, we would be seeing bowel and all sorts of interesting things bulging and squeezing away. So the abdominal wall covers it up, but if it was just skin and fat, then neither of these things is particularly strong and the the abdomen would easily stretch and bulge. The strength in the abdominal wall (obviously) comes from the muscle layer. The very same muscle layer through which the blood vessels we need for a DIEP (or TRAM) flap pass. And therein lies our issue.
When I raise a DIEP flap, I chase those perforating blood vessels through the sheath of the (rectus) muscle, into the muscle and right out the back of the muscle and down into the groin. As I do this, I come across the tiny nerves that allow the muscle to contract and support the abodmen. If those nerves are damaged, then possibly the ability of that muscle to work is compromised. If a TRAM flap is raised instead, then the muscle itself is sacrificed. And without the muscle either working or present, the remaining layers of the abdominal wall just don’t have the strength to support all the stuff on the inside from bulging outwards!
2. SO, HOW CAN BULGES AND HERNIAS AT THE DIEP FLAP DONOR SITE BE PREVENTED OR AVOIDED?
The best answer (although perhaps the most controversial) is to only ever raise DIEP flaps, and when doing so, protect those tiny little nerves. This may sound straight forward, but believe me it isn’t so. Some of those little nerves are truly tiny, sometimes the nerves get caught up in the blood vessels and have to be cut to allow the flap to be raised, and there is some conjecture as to whether the muscle ever works the same way again at the DIEP flap donor site anyway. And sometimes, a DIEP just isn’t possible.
If a TRAM flap cannot be avoided, there are ways to decrease the risk of hernias and bulges. This can depend on how much muscle and how much of the muscle sheath is harvested with the flap, but the simplest way to decrease the chance of bulges and hernias is to use a “mesh” when repairing the abdomen. This involves placing a permanent woven sheet of prosthetic material into the abdomen, under the muscle sheath which heals into the muscle sheath with scar. As it does so, it strengthens the abdominal wall as the muscle would have previously, although obviously, it can’t contract like a muscle would. Even if the mesh doesn’t quite work like a muscle, many authors have found that by using a mesh after a TRAM flap, the risk of hernia is no higher than with DIEP flaps.
3. HOW MUCH BETTER IS THE DIEP FLAP REALLY?
Like everything in this game, this answer can depend an awful lot on who you ask. So ask the right person!
By nature, I tend to be a little skeptical when anyone claims that one thing is better than another, and so it was for me with the superiority of DIEP flaps over TRAM flaps. This had a lot to do with the fact that it is really only in the last few years that we have gained enough data to really have any idea about this. We have to remember that DIEP flaps have only been around in really widespread usage for maybe 5-10 years: in fact, there are still many, many surgeons who either choose not to or don’ t have the skill to perform DIEP flaps. In surgical terms, it is still a relatively new procedure. As a consequence, the early publications claiming that the DIEP was better, I read with a degree of doubt. But, I have come around (sort of….see below). This has been driven by my own experience and also by the more recent work from America and the UK.
Lets start with my experience: I’ve seen one, and only one hernia develop after a DIEP flap. This lovely lady came to see me about 4 or 5 months surgery with a bulge at her DIEP flap donor site that would appear to have developed between 2 & 3 months after her surgery. The most memorable thing was the story she told me. This lady had had an upper respiratory tract infection some weeks prior. She had developed a persistent cough, which dragged out over many weeks, and it was during a coughing fit that she felt a very distinct tearing sensation as the stitch holding the muscle sheath together popped with the strain of her coughing.
I think that any one person’s experience is never enough information to form a true opinion, unless that person has several thousand cases under their belt (and there aren’t many surgeons with that much experience!). So, I look to the published data for more information. The best part about that, is that one of the largest studies ever performed looking at the risk of donor site hernia, was written by one of my registrars in the UK. In her paper published last year, which looked at nearly 8000 (!) TRAM and DIEP flap breast reconstructions, they found that free TRAM flaps had a higher incidence over time of hernia (a hazard ratio of 1.8), when compared to DIEP flaps.
Similar findings have been replicated in recent years in many different papers, but I think it is worth highlighting another paper from Andrea Pusic (who I have mentioned previously) in New York, published earlier this year. Dr Pusic (who you may recall developed the Breast-Q patient rated outcome tool) found that when comparing DIEP flaps to “free” TRAM flaps, whilst differences were present, the differences were not statistically significant (which simply means that the differences could have been due to chance). The interesting fact about this paper is that based specifically on various components of the Breast-Q related to abdominal “well-being”, the DIEP flap was neither associated with lower rate of hernia, nor with improved patient ratings of “well-being” compared to most free TRAM flaps. The lack of significant difference between DIEP flaps and TRAM flaps irrespective of how much of the muscle was sacrificed highlights the ongoing contention in this regard as to the superiority of DIEP flaps over TRAM flaps
SO, WHERE DOES THAT LEAVE US?
I approach this problem is the simplest way that I can. This is what I tell my patients.
The risk of hernia after abdominal free flap harvest is small but significant. It is hard to properly quantify because the reported incidence is so variable in the literature. Whether the DIEP flap donor site has a lower chance of hernia formation than TRAM flap donor sites, I don’t worry about too much. The simple fact is that when the difference between the two techniques is so small anyway, I don’t think the risk of hernia can be used as justification for performing one flap over another. I do DIEP flaps for reasons that really have nothing to do with the possibly lower rate of hernia. I consider DIEP flaps better than TRAM flaps primarily because I find the operation more user friendly (for me) than a TRAM. This has a lot to do with the way in which the blood vessels lie when the flap is moved to the chest for the microsurgery: without all the bulk of the rectus muscle, I find the microsurgery much easier. And given that most of my experience is with DIEP flaps rather than TRAM flaps, I am very comfortable performing the DIEP flap, so why wouldn’t I do it. I feel that the DIEP flap provides me with a more reliable procedure and that translates into a lower risk for my patients, especially when it comes to microsurgery.
For a surgeon more used to doing TRAM flaps however, trying to do a DIEP flap (which may be unfamiliar) just because some papers in the literature suggest a lower risk of hernia is ridiculous. If a surgeon is unfamiliar with the techniques required for a DIEP flap, then there is a much higher risk of damage to the pedicle or partial flap loss, and this far outweighs the possible benefit of a DIEP from the perspective of hernia risk.
The short answer: your surgeon should do the flap that he or she feels most comfortable with, to ensure that the risk to the flap is the lowest it can be. I am still not convinced that the rate of hernia is significantly lower for DIEP flaps, and that is why I don’t try to justify what I do on those grounds. I do DIEP flaps because I find them easier to deal with than TRAM flaps. Simple as that. If the risk of hernia after DIEP flap is lower (and I suspect it is) then that is an added bonus for my patients.
The risk of hernia is just one of those things which I believe has to be accepted as a possibility, but don’t let it be another thing to worry about before going ahead with breast reconstruction.